Braking apparatus



Jan. 10, 1961 I J. B. OTTESTAD 2,967,590

BRAKING APPARATUS Filed July 16, 1957 m m N INVENTOR.

JACK B. OTTESTAD BYghlca ATTORNEY United States .nature.

BRAKING APPARATUS Jack B. Ottestad, Claremont, Califi, assignor toGeneral Dynamics Corporation, San Diego, Calif., a corporation ofDelaware Filed July 16, 1957, Ser. No. 672,179

3 Claims. (Cl. 188-41) The present invention relates to an apparatus forbraking a moving body, and more particularly relates to such anapparatus which is adapted to move with the body to be braked.

An application for which the present invention is particularly wellsuited, although it is not limited thereto, is the deceleration of workplatforms or carriages which are moving at high velocities. Thus, in thefield of shock-testing of components such as electronic units or thelike,the behavior and reliability of such components is conventionallydetermined by subjecting them to high initial accelerations or G loadsprovided, for example, by apparatus such as that described in mycopending patent application Serial No. 617,014, filed October 19, 1956.c It will be apparent that once a component or unit is subjected to adesired high initial acceleration, the carriage or structure supportingthe unit should be slowed or retarded as quickly as possible to keep thelength of the test structure to a minimum. The arresting gear or energyabsorption devices used by the prior art to accomplish this desiredretardation have not been completely satisfactory for various reasons,including their unwieldy nature, unpredictable operation, weight,expense, and difliculty of maintenance. Typical examples of previousenergy absorption devices are collapsed lead block, stretched steeltraps, and hydraulic shock absorbers, each of which is unwieldy orrelatively complex in Moreover, these prior devices are generally notsufiiciently compact to be moved or carried with the body to' be tested,and a desirable simplicity and reduction of parts in the decelerationapparatus is consequent- 1y lost. Further, the deceleration provided bycertain of such devices is destructively abrupt and incapable ofadjustment, in contrast to the desired retardation which ischaracterizedby an adjustable and controlled deceleration-time pattern.

Accordingly, the present invention comprises a braking or decelerationapparatus which may be carried by the carriage to which the testspecimen or work piece is mounted. The apparatus is adapted to act inbraking fashion against the columns or rails which serve to support orguide the carriage, is compactly contained within the carriage, andincludes fluid-actuated piston elements which provide the braking orretarding action by reason of their frictional engagement with thecarriage supporting rails. The degree of retardation is controllable byadjusting the fluid pressure applied against the piston elements, and itwill be apparent that the decelerationtime pattern is repeatable, cyclefor cycle, merely by maintaining a constant pressure against the pistonelements.

Although a particular application or use for the present apparatus willhereinafter be described, it is to be understood of course that theparticular application is merely by way of example, and not by way oflimitation. For, example, the present apparatus is also adapted for usein braking the platens of metal forming machinery.

atentO ICC These platens do not generally travel at the highervelocities of shock-testing carriages, but the problem of braking isessentially the same, and as will be apparent, the present invention iseffective to provide such braking. The present device will be describedin connection with an actuator of the type set forth in the abovesaidpatent application Serial No. 617,014, although, as will be apparent,the particular type of actuator for driving the work platform or testcarriage is not critical.

The level of initial thrust provided by the abovesaid actuator isrelatively large with respect to the braking action provided by thepresent deceleration apparatus, so that fluid pressure may be applied tothe braking elements of the present apparatus during the complete strokeof the actuator. Since the braking eflect of the present apparatus willbe so comparatively negligible during the initial portion of theactuator stroke, the decelerative effect of the apparatus will therebybe desirably postponed until the end of the actuator stroke, at whichtime the piston elements will desirably slow and limit the actuatorstroke. But for the use of some such braking apparatus, the decelerativeeflect of friction and gravity forces would be incapable of slowing thecarriage and limiting its travel to an acceptable degree, and the lengthof side rails would be prohibitive. Moreover, as will become moreapparent in the description hereinafter made, the present apparatus isrelatively inexpensive to fabricate, comparatively easy to maintain,compact, and light in weight.

It is therefore an object of the present invention to provide animproved braking apparatus which is adapted to move with the body to bebraked.

It is another object of the present invention to pro- .vide a uniquelight-weight apparatus for braking a moving body, and which ischaracterized by braking elements actuated by fluid pressure.

A further object of the present invention is the provision of a noveldeceleration apparatus which is adapted to retard a moving body in amanner characterized by a predetermined and controlled deceleration-timepattern.

Another object of the invention is to provide an improved energyabsorption device for slowing a carriage movable upon rails, and whichis adapted to frictionally engage such side rails by means of aplurality of braking elements acting under the influence of fluidpressure.

Still another object of the present invention is the provision ofbraking apparatus which is characterized by light weight, simplicity ofoperation, ease of manufacture, and compactness.

Other objects and features of the present invention will be readilyapparent to those skilled in the art from the following specificationand appended drawings wherein is illustrated an embodiment of theinvention, and in which: 7

Figure 1 is an elevational view of the braking apparatus of the presentinvention mounted in operating relationship with an actuator and thecarriage and supporting structure for such actuator;

Figure 2 is a plan view of that which is illustrated in Figure 1;

Figure 3 is asectional view taken along line III-III of Figure 2; and

Figure 4 is a sectional view taken along the line IV-- IVof Figure l.

Referring to the drawings, there is illustrated an embodiment of thebraking apparatus of the present invention which is generally designated11, and which is adapted for association with an actuator of the typedescribed and fully set forth in the above-said copendingpatentapplication SerialNo. 617,014. Such actuatoris generallydesignated 12, and is illustrated in association with usual supportingstructure 13, which includes a base plate 14 resting upon the floor, abox-like housing 15 rigidly secured to base plate 14 and serving toenclose the greater part of actuator 12, and an intermediate plate 16which is fixed to housing 15 to rigidity the supporting structure 13, aswill be apparent. The lower end of actuator 12 rests upon base plate 14,and the upper end thereof extends through a suitable opening cut in theupper or cover portion of housing 15. Actuator 12 also extends throughan opening provided in plate 16, and in this manner actuator 12 issecurely maintained in operative position to drive its thrust column 17against a body support structure, work platform, or carriage 18.

Carriage 18 is slidably movable along and extends laterally between apair of ways, columns, or side rails 19, and is adapted to carry aworkpiece or test specimen 21 upon its upper surface, as illustrated.Upon firing of actuator 12, it will be apparent that specimen 21 will bedriven with carriage 18 along side rails 19, thereby subjecting specimen21 to the particular thrust or G loads of which actuator 12 is capable.

Side rails 19 are rigidly anchored in position by securement tostructure 13, and rigidly carry, respectively, lower end fittings 22,intermediate fittings 23, and upper end fittings 24. Fittings 22 restupon base plate 14, fittings 23 are securely fastened to intermediateplate 16, and fittings 24 are rigidly secured to the cover plate ofhousing 15 whereby rails 19 are maintained vertical and parallel and arerestrained against upward and downward movement, as viewed in Figure 1.Rails 19 are each capped at their upper ends with a stop nut 25 topositively limit upward travel of carriage 18 in the event apparatus 11carried by carriage 18 should fail to operate for some unforeseenreason.

As best illustrated in Figures 3 and 4, carriage 18 comprises asubstantially diamond shaped upper cover 26, a similarly shaped lowercover 27, and a pair of arcuate end members 28, only one of which isillustrated in Figures 3 and 4. Members 28 are located at opposite endsof covers 26 and 27 and serve to assist in maintaining covers 26 and 27in parallel, spaced apart relationship, covers 26 and 27 each beingsecured to members 28 by a plurality of machine screws or the like, asat 29. In addition, a pair of side covers 31 and 32 are welded orotherwise secured to the ends of members 28 and to the edges of plates25 and 26 to form a substantially closed diamond-shaped container whichserves to house braking apparatus 11, aswill be seen.

Covers 26 and 27 are provided at their lateral end portions withvertically aligned openings for the accommodation of support tubes 33.The upper portions of tubes 33 fit within and through these openings,while the lower portions of tubes 33 are slightly larger in diameter ascompared to the upper portions whereby they each abut lower cover 27 ata peripheral shoulder 34. It is noted also that the inner diameter ofeach tube 33 is sufiiciently greater than the outer diameter of thecorresponding rail 19 so that no interference occurs therebetween and afreely slidable spaced relationship exists.

The upper and lower ends of each tube 33 are threaded to accept,respectively, a pair of threaded retainer nuts 35 each of which has aninwardly directed annular shoulder portion adapted to slidably contacttube 33 whereby the shoulder portions of nuts 35 provide the bearingcontacts between carriage 18 and rails 19. For this purpose, nuts 35 maybe made of any suitable bearing material, such as bronze or the like, toprevent sticking and galling. It will be apparent that the upperretainer nut 35 also serves to maintain tube 33 and the assembly ofcovers 26 and 27 in rigid relationship.

Braking apparatus 11 includes a cylinder 36 which is disposed laterallybetween support tubes 33 and within the space defined between uppercover 26 and lower cover 27. The ends of cylinder 36 are cut in arcuateform so as to closely abut and mate with tubes 33, and the upper andlower surfaces of cylinder 36 are formed or cut to present fiat faces tocovers 26 and 27. Thus the bearing area of covers 26 and 27 againstcylinder 36 is adequate to prevent cylinder 36 from rolling out ofposition, and a plurality of retainer bolt and spacer assemblies 37 areprovided to assist in this regard. Assemblies 37, only two of which areillustrated, are rigidly fixed in vertical relationship between covers26 and 27 along the length of cylinder 36, and maintain cylinder 36 inposition by bearing against cylinder 36 at their sides.

Cylinder 36 serves to slidably acommodate a pair of pistons 38, only oneof which is illustrated, which are operable outwardly toward side rails19 under the urging of fiuid pressure admissible through a pressurefitting 39 located between pistons 38. Fitting 39 is disposed through asuitable opening 41 provided therefor in lower cover 27, and is threadedinto a threaded bore provided in the lower face of cylinder 36 wherebyfluid communication may be had between the interior of cylinder 36 and afluid pressure line (not shown) connected to fitting 39.

Each piston 38 is made to be fairly light in weight, being internallybored at 42 and provided with an annular reduced diameter portion 43 formaterial removal and consequent weight reduction. By this means eachpiston 38 is highly responsive to fluid pressure acting through fitting39 and against its inner face 44. In addition, fluid tight relationshipbetween each piston 38 and the inner walls of cylinder 36 is promoted bythe provision of a suitable pressure seal or 0 ring 45 in a peripheralgroove at the inner end portion of piston 38.

The outer end of each piston 38 is formed to accommodate a brakeelement, face, or shoe 46 which is made of a suitable brake material,such as asbestos or the like, for frictional engagement with itsassociated side rail 19. Shoe 46 is securely fastened to the outwardface of piston 38 by any suitable means, but preferably by the processof adhesive bonding well known to those skilled in the art.

To permit shoes 46 of pistons 38 to come into frictional engagement withside rails 19, tubes 33 are each provided with a transverse boretherethrough. Each piston shoe 46 may thus be urged through the wall oftube 33 and against a rail 19 by the action of fluid pressure withincylinder 36.

Each piston 38 is maintained in operative orientation with respect toits associated rail 19 by a stop means or short pin 47 which is securedto piston 38, as best illustrated in Figure 3, and which is carriedwithin a slot 48 formed in the outward end of cylinder 36. It will beapparent that inward and rotational movements of each piston 38 are thuslimited by contact or engagement between its stop pin 47 and associatedslot 48 so that pistons 38 are always in position to be urged intofunctional engagement with side rails 19.

In operation, fluid pressure is admitted to cylinder 36 while carriage18 is in the downward position illustrated in Figure 1. This urgespistons 38 into functional or braking engagement with side rails 19.Next, actuator 12 is fired and thrust column 17 is thereby urgedupwardly against carriage 18. Since the retarding or braking forceprovided by pistons 38 acting against rails 19 is relatively smallcompared to the upward force exerted by actuator 12 against carriage 18,carriage 18 will be urged upwardly by thrust column 17. The desiredinitial high G or acceleration forces generated by actuator 12 are thusoperative upon specimen 21 carried by carriage 18. As the initial highvalue of thrust of actuator 12 decays, the braking effect of brakingapparatus 11 is increasingly felt, and carriage 18 will be comparativelygradually snubbed to a standstill somewhat short of stop bolts 25. Ifdesired, the pressure applied to cylinder 36 may be appliedsubstantially instantaneously after a predetermined upward travel ofcarriage 18, or the pressure may be varied in accordance with somepredetermined pattern. In any event, it will be apparent that theretardation, deceleration, or braking of carriage 18 can be made toconform to a predetermined deceleration-time pattern if desired, andthat the braking action provided by apparatus 11 may be adjusted andcontrolled. Moreover, it will also be apparent that by reason of theactuation of both pistons. 38 by a common fluid pressure within cylinder36, the braking action of apparatus 11 is stabilized and balancedbetween the pair of side rails 19.

While certain preferred embodiments of the invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto as many variations will be readily apparent to thoseskilled in the art and the invention is to be given its broadestpossible interpretation within the terms of the following claims.

I claim:

1. A braking apparatus adapted for movement with respect to a pair ofWays, said apparatus comprising support means in slidable encompassingengagement with said ways, said support means having bore means, acylinder, a pair of pistons carried within said cylinder and arranged tobe urged into frictional engagement with said pair of ways through saidbore means, respectively, and means for admitting fluid pressure to saidcylinder between said pair of pistons thereby to effect a substantiallybalanced braking action by said pair of pistons against said pair ofways whereby relative movement between said support means and said pairof ways is retarded in stabilized manner.

2. A braking apparatus for movement with respect to way means, saidapparatus comprising support means in slidable encompassing engagementwith said way means, said support means having bore means, a cylinder, apair of pistons carried within said cylinder and arranged to be urgedinto frictional engagement with said way means through said bore means,means including a fluid inlet located between said pair of pistons foradmitting fluid pressure to said cylinder therebyto effect engagementbetween said pair of pistons and said way 6 means whereby relativemovement between said support means and said way means is retarded, andstop means disposed between said cylinder and said pair of pistons tolimit travel of said pair of pistons away from said way means wherebysaid pair of pistons will be maintained in operative orientation withrespect to said fluid inlet.

3. In the combination of a body support structure, in slidableencompassing engagement with a pair of rails, an actuator for eflectingmovement of said body support structure along said pair of rails; animproved apparatus for braking said body support structure during saidmovement, said apparatus comprising an open-ended cylinder mountedwithin said body support structure with the open ends thereof adjacentsaid pair of rails, a pair of pistons carried within said open ends,respectively, of said cylinder, brake shoes carried by said pair ofpistons, stop elements disposed between said cylinder and said pair ofpistons to maintain said pair of pistons in position adjacent said pairof rails, and means for admitting fluid pressure to said cylinderthereby to effect engagement between said pair of rails and said brakeshoes of said pair of pistons whereby said body support structure isrestrained against movement.

References Cited in the file of this patent UNITED STATES PATENTS1,382,211 Miller June 2, 1921 1,503,882 Castleman Aug. 5, 1924 2,103,708Campbell Dec. 28, 1937 2,407,655 Di Santi Sept. 17, 1946 2,792,081 GolobMay 14, 1957 2,792,091 Beck et al. May 14, 1957 2,856,200 Conflitti Oct.14, 1958 FOREIGN PATENTS 112,235 Austria Feb. 11, 1929 944,111 FranceOct. 25, 1948 741,611 Germany Mar. 23, 1953

